1. Field of the Invention
The present invention relates to a method, a device and a computer-readable recording medium containing a program for extracting an object region of interest from an image, and in particular to a method, a device and a computer-readable recording medium containing a program for extracting an object region of interest, such as a lesion region or an organ region from a medical image.
2. Description of the Related Art
In the medical field, a process of extracting and displaying a certain object region of interest, such as a lesion region or an organ region, from a medical image has conventionally been conducted to provide an image with high diagnosis performance.
An example of the method for extracting an object region from an image is described, for example, in US Patent Application Publication No. 20040008886, where the user specifies certain pixels in the image representing an object region and other certain pixels in the image representing a background region. Then, a probability indicating whether each pixel represents the object or the background is calculated based on information of the marked pixels, and a probability indicating whether or not each combination of neighboring pixels are pixels belonging to the same region is calculated based on a local density difference in the image. Then, the object region is extracted from the image using these probabilities.
Another example of the method for extracting an object region from an image is proposed in R. Tachibana and S. Kido, “Automatic segmentation of pulmonary nodules on CT images by use of NCI Lung Image Database Consortium”, Proc. of SPIE, Vol. 6144, pp. 61440M-1-61440M-9, 2006 where the user specifies certain pixels in the image representing an object region and other certain pixels in the image representing a background region, and these pixels are respectively used as reference points for region growing for the object region and reference points for region growing for the background region. Then, a probability indicating whether or not each combination of neighboring pixels are pixels belonging to the same region is calculated based on a local density difference in the image. Then, each reference point is subjected to region growing using the probability, and a boundary is created along points where the grown object region and the grown background region meet, to extract the object region from the image.
In the techniques proposed in these documents, however, the user is required to manually specify certain pixels representing an object region and other certain pixels representing a background region in the image, and this is troublesome. Therefore, it is desired to reduce troublesomeness of the manual input by the user.